For a long time, the construction method of steel penstock of a hydraulic turbine is: after the steel penstock is installed, concrete is poured at their outsides; meanwhile or later, a volute of the hydraulic turbine is then installed. The encased concrete is backfilled and then the volute is fixed. The remaining connecting sections between the steel penstock and the volute are installed and welded in the end, and the concrete is backfilled after they are inspected, accepted and qualified. Generally, a joint installed and welded by split tiles is adopted for short connection sections while a joint of split tiles connected with complete pipeline is adopted for long connection sections. The connection sections finally form two annular welds which are in butt weld. Limited by the method, it will cause the following problems: firstly, very strong welding shrinking stress will occur under the conditions that the two ends are restrained, thereby bring the adverse effect to the quality of the hydraulic turbine installation. The bigger the hydraulic turbine is, the stronger the adverse effect is, correspondingly. Therefore, the technical problems caused by the defects of the method can be alleviated in the prior design or construction of the hydraulic turbine at relatively high cost. Secondly, as there are installation errors between the steel pipelines and the volute which have been installed and fixed, the relatively big error will cause the size of the tiles or pipeline joints not to be effectively controlled, thereby causing difficulty for the prefabrication in a plant. Therefore, the construction period and cost of the connection sections are out of control. Thirdly, as the prior method is limited under the transport and hoisting conditions, the workers have to bear high working strength but receive low work efficiency. As for the abovementioned problems, the method that the whole section of a steel pipeline is hoisted is proposed and applied in some construction projects. Measures, such as the increases of the installation positions and dimensional precision of an outlet of the steel penstock and those of an inlet of the volute, strict control for the manufacturing quality of steel plants and so on, are adopted. However, it is needed to improve the technical standard of the installation of the pipeline at two connection openings at the two ends thereof; furthermore, prefabricated steel pipelines should strictly meet the requirements of manufacturing quality. Even so, adverse effects of the shrinkage stress under welding can not be fundamentally eliminated. In addition, it takes 30-40 days of the time limit of a project to complete the installation of one connection section. China Patent Applications No. 2005100203967 and No. 2006100201010 respectively propose a large scale steel pipe automation process and a large scale steel-pipeline trolley, which provide basic conditions to the field mechanism rapid construction of the steel penstock. But it does not relate to the installation order of the water-diversion steel pipeline. If the prior problem of the connection section between the steel pipeline and the volute is to be solved, and the manufacturing quality and construction efficiency of the water-diversion steel pipeline are further improved, the prior construction method must be improved.